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B0486
12-04-2003, 09:47 AM
I'm posting this on various forums for discussion and comments:

I was contacted privately by another forum member who had seen previous posts about our/my observations regarding serrations and their effectiveness or non effectiveness against different types of outer clothing vs. plain edged of the same design.

This person took the time to cut a dungaree jacket with a half serrated recurved blade of 4 inches in length. He wrote as his observations and findings were somewhat different than the findings of the class in LR many years ago. He thought I should be aware of these findings and asked me to comment on the disparity between the findings and possibly an educated guess as to why the disparity.

In previous classes years ago [ not in the last 6 years ]we saw that serrations would drag/grab scertain material slowing the blade and effectively reducing the depth of the cut made through the medium [ material we were cutting ]when checked against the plain edge on the same materials.

His recent observations with the half serrated blade showed that the serrations dug deep, did not drag and produced very nasty cuts to the material vs a plain edgeed blade of the same design.

We talked a bit over emails and I recommended that he post his results on the forums for all to be able have the information available to them here and as well, bring this discussion to the forefront with others impressions and comments.

He and I both agreed the half serrated would not have been as effective at the cutting performance if it had been fully serrated as more teeth would mean more drag. We also agreed the recurve of the blade [ blade design ] may have played a role in the results as well.

I also suggested that the teeth of serrated knives are of somewhat different design dependant on different makers. For instance, the spyderco serrations from the early days on certain models [ and continuing to this day ] are cut deeper [ have longer teeth height ] than other makers serrations. The serrateds tooth design will also affect the outcome of whether one is better than another.

We discovered that there are many variables and disparities between makers blade designs and teeth configuraions to include the height of the teeth as well as the overall pattern to the teeth which is also different dependant on model and maker. Serration designs have also evolved to a degree where they are shallower [ less toothy and consequently less aggressive ] than the early daysas a rule. This may be due to observations of their own testing data or perhaps from listening to the buying public and attempting to compromise between too aggressive and not very aggressive.

All the above can skewer the results one has and so we are now left with a few choices to make. Some serrations obviously cut better through material than others. Dependant on the maker and model, tooth design, etc the serrated knife may or may not be a better choice for self defense over a plain edge.

In the future, I'll not quote our own testing results of years past as the time passed has brought forth many changes in the industry and one can not hold an objective view if they hold onto old data and do not continue to retest the designs and patterns of serrations from different makers vs. the plain edge in the same guise.

Comments?

Brownie

michael
12-04-2003, 11:51 AM
I think you're right on the mark. I know a fellow who is a very high ranking martial artist, former USMC, former DIA and now CIA. "They", and I'm not sure if it was for the government or his own students, did extensive testing of serrated vs. unserrated blades, cutting meat clothed in denim (I think it was 2 layers). His conclusions were that the unserrated blades made deeper and smoother cuts. They reasoned that the serrated edges caused minute "bouncing" of the blade as it cut, which caused it to not cut as deeply or as smoothly. I believe he used fully serrated blades and not half-serrated for all of his testing.

One other thing he talked about was blade length in folding knives (not full-length fighting blades). He concluded that a 3" blade makes a deeper cut than a 4" blade because you can get more force delivered to the blade the smaller the blade length. In certain respects this does make sense, but I can see both sides to this conclusion. Brownie, have you conducted testing like this and, if so, what were you're conclusions? I'm sure the knife steel and quality has a lot to do with it, but quality and steel being equal, which one cuts deeper?

B0486
12-04-2003, 12:35 PM
michael:

Based on my own testing and as objective as possible findings between full serrated and plain edge [ with the same knife in the two configurations ], the PE cuts deeper if it is kept very sharp.

The SE's we tested, and they may not all be equal, did catch material slowing the blade somewhat which resulted in less severe cuts to the medium.

If the serrated is put against a straight edge and the SE is not as sharp as can be, the serrated will produce deeper wound channels all things being equal otherwise.

Your friends findings run equal to my own and others I have witnessed.

I do not carry serrated for defense. I do carry razor blade [ scary sharp ] sharp knives at all times. These knives are reserved for no other purpose but to save my bacon and so stay razor sharp until I need them [ hopefully that never happens ].

Tell the jarhead I said hello when you see him.

Stay sharp

Brownie

michael
12-04-2003, 03:09 PM
Brownie,
Thanks for the info. I also carry only unserrated blades for defense and, like you, I keep them razor sharp and do not use them for anything else. What about the blade lengths and their cutting ability?
Thanks.

B0486
12-04-2003, 09:14 PM
I see two camps/views emerging on folders relative blade length and the differences in performance defensively.

One states the shorter blades [ 3-4" ] will be better leveraged, properly used, and will be more stable in the hand affording more force being applied to resistance.

The others state the longer blades [4-6" or better ] will be less stable and afford less force applied to resistance and that the longer blade has the capability to get deeper cuts and has more blade available to creatre deeper wounds.

I hadn't thought much about it until I heard the different views fairly recently.

I've always carried folders in the 3 1/2, up close to 5 inches for defense. I have always liked the smaller blades for their quick to point from pocket and control.

I'm presently carrying an SnG [ defensive ]which is a small bladed folder and the ER MPC, but this one is not for defensive purposes though it could be easily.

Some 4 1/2 inch models are very fast to point, alas, they are linerlocks and are not found in my pockets anymore. Just don't trust them as much as I used to and there are other choices that suffice nicely.

I think length does give advantage, and would carry the Bagwell if I knew I was going to need a blade. Day in and day out, the smaller folders are a compromise of sorts but are very fast out of the pockets and are there when needed.

Brownie

michael
12-05-2003, 07:38 AM
Thanks for the info. I would love to see some objective test results on blade length. If you ever come across any, please post them. Both sides of this argument make since and I'm not sure which one is correct. So I carry both.:D:D

InTheBlack
12-08-2003, 10:06 PM
It would be interesting to see an image showing some of the various serration designs which are out there. Followed of course by testing...

If a blade is being slashed or dragged, doesn't the hilt end do the cutting of the surface material, and the point end is deeper in the target?

So why not put the smooth edge to the rear and the serrations to the front, if in fact serrations produce a better wound profile?

And to cover all the bases, maybe make the first half inch of the tip smooth, to optimize a stab or initial slashing penetration?

What's the functional purpose of having the serrations towards the hilt on a half-serrated blade???

Matt
12-09-2003, 09:28 AM
alas, they are linerlocks


Maybe I've been out of the loop for awhile, but why don't you like liner locks?

B0486
12-09-2003, 10:16 AM
Hi Matt,

Some of my best folders are linerlocks. I used to carry them exclusively for the last decade until this year. There are many models to choose from from various makers giving one a good selection of defensive folders.

I no longer carry them as I do not trust them to stay locked under hard use conditions. By hard use I mean a dynamic defensive scenario.

Linerlocks suffer from a few problems, all lock related.

1. The lock may not mate correctly to the blade, when opened and locked, which will allow lateral stresses to unlock the blade during use.
2. The liner may "bounce" off the blade releasing/unlocking during use
3. The linerlock may disengage if pressure is applied to the spine of the knife.
a. This can be a shock force [ sudden blow to the back of the blade.
b. This can be steady pressure to the spine of the knife.

Some makers can't get the lock correct and have a reputation with this probelm.

The linerlock, by it's design, will constantly wear on the mating surfaces of the lock and blade affecting the stability and dependability of the lock. It may pass the spinewhack test today and fail tomorrow under the same test [ theoretically, though one day would probably not change the locking surfaces unless the blade had been opened and closed a thousand times ].

As such, they are unacceptable to me as I can not be fairly certain if the blade is twisted laterally or takes a bump to the spine of the knife that it won't unlock taking my fingers off ] no thankyou ].

As well, I have had linerlocks in the pockets tip up and had the blade barely open so when I dove for it I stabbed my thumb. This would be "not good" if I was actually attempting to deploy the folder to defend myself. This has happened twice to me and others have reported the same results.

So if you carry a linerlock, be aware of the dangers of tip up and as well the reasons stated why I no longer trust them as EDC defensive folders.

OMMV of course. I like them but do not trust them completely and so will not carry them.

Brownie

Matt
12-09-2003, 10:35 AM
Wow - thanks for all the info. Which design do you prefer?

I'd agree - I don't like the "tip up" carry either. It just seemed to easy to have it open on the way out, or catch on something, or stab you in the tumb if it were open.

I'm curious, though - I have an older model Benchmade, in the Emerson design (before he split from them), with the titanium liner locks that I've carried for a long time and still seems very tight and I've been happy with (although I admit I use it more for day-to-day chores than anything else).

Is this one of those that has the "bad reputation"?

Is there anything I should be on the lookout for as far as wear goes?

B0486
12-09-2003, 10:50 AM
Hi Matt,

watch ther liner when locked open. How far does it run across the face of the blade it contacts.

New liners should sit somewhere about 1/2 the blades width, then they wear further to the "inside" as time goes on and they are used.

If the liner is engaged, locked open, and the liner is all the way to the opposite side of the blade, it will be near the end of it's lifespan.

Some liners will wear faster than others. Some, like the Spyderco Millie haven't worn much in the last several years. Just keep and eye on how far the liner is moving in on the blade surface.

The Benchmade Emerson designed knives faired very well for dependability. Their linerlocks were not ones prone to failure new or with use [ buyer beware, of course ].

I have had to send back several Emersons for customers right out of the box as the linerlock disengaged under pressure on the spine or the spinewhack test.

Take that for what it's worth. I no longer will order certain models from that maker for customers. It's too much hasstle to send them back.

I presently carry a Strider SnG 3rd model as a defensive EDC and I also carry 24/7 the Extrema Ratio MPC for anything that may require hard use or abuse.

The SnG isa framelock. Though they are similiar to a linerlock [ in theory ] the framelocks do not suffer the same fate as the linerlocks very often in any model or make. As well, the harder you grip the knife the more the lock is forced to stay engaged. If it were to start to give, your hand/fingers would feel the framelock moving.

I like lockbacks for heavyduty use, whether for defense or GP cutting chores. These are all personal preferences and not endorsements or disparages for any product.

Brownie





Brownie.

Brownie